Migration has a vital function in forming the body plan of an organism and yet underlies the process of metastasis in cancer. Although the cell biology of migration has traditionally been studied in vitro, an in vivo system is required to relate this process to both development and disease. This study will investigate the migration of an individual cell in C. elegans, using both genetic and cell biological approaches, with the goal of understanding how genes function in a molecular pathway to ultimately regulate the cell biology of migration. Specifically, the migration of the linker cell (LC), which is the leader cell for gonad migration in the male, will be examined using three approaches. Molecular markers based on green fluorescent protein (GFP) will be developed to examine in live animals the LC, its surrounding extracellular matrix, and its intracellular polarity as it migrates. A screen using the RNAi library will be conducted to identify genes involved in LC migration. Finally, by using the molecular markers described above and building new tools, such as translational reporters, the function of selected genes and gene networks in regulating the cell biology of migration will be investigated.